/
graph.rs
490 lines (415 loc) · 15.3 KB
/
graph.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! A graph module for use in dataflow, region resolution, and elsewhere.
//!
//! # Interface details
//!
//! You customize the graph by specifying a "node data" type `N` and an
//! "edge data" type `E`. You can then later gain access (mutable or
//! immutable) to these "user-data" bits. Currently, you can only add
//! nodes or edges to the graph. You cannot remove or modify them once
//! added. This could be changed if we have a need.
//!
//! # Implementation details
//!
//! The main tricky thing about this code is the way that edges are
//! stored. The edges are stored in a central array, but they are also
//! threaded onto two linked lists for each node, one for incoming edges
//! and one for outgoing edges. Note that every edge is a member of some
//! incoming list and some outgoing list. Basically you can load the
//! first index of the linked list from the node data structures (the
//! field `first_edge`) and then, for each edge, load the next index from
//! the field `next_edge`). Each of those fields is an array that should
//! be indexed by the direction (see the type `Direction`).
#![allow(dead_code)] // still WIP
use std::fmt::{Formatter, Error, Show};
use std::uint;
use std::collections::BitvSet;
pub struct Graph<N,E> {
nodes: Vec<Node<N>> ,
edges: Vec<Edge<E>> ,
}
pub struct Node<N> {
first_edge: [EdgeIndex, ..2], // see module comment
pub data: N,
}
pub struct Edge<E> {
next_edge: [EdgeIndex, ..2], // see module comment
source: NodeIndex,
target: NodeIndex,
pub data: E,
}
impl<E: Show> Show for Edge<E> {
fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
write!(f, "Edge {{ next_edge: [{}, {}], source: {}, target: {}, data: {} }}",
self.next_edge[0], self.next_edge[1], self.source,
self.target, self.data)
}
}
#[deriving(Clone, PartialEq, Show)]
pub struct NodeIndex(pub uint);
#[allow(non_upper_case_globals)]
pub const InvalidNodeIndex: NodeIndex = NodeIndex(uint::MAX);
impl Copy for NodeIndex {}
#[deriving(PartialEq, Show)]
pub struct EdgeIndex(pub uint);
#[allow(non_upper_case_globals)]
pub const InvalidEdgeIndex: EdgeIndex = EdgeIndex(uint::MAX);
impl Copy for EdgeIndex {}
// Use a private field here to guarantee no more instances are created:
#[deriving(Show)]
pub struct Direction { repr: uint }
#[allow(non_upper_case_globals)]
pub const Outgoing: Direction = Direction { repr: 0 };
#[allow(non_upper_case_globals)]
pub const Incoming: Direction = Direction { repr: 1 };
impl Copy for Direction {}
impl NodeIndex {
fn get(&self) -> uint { let NodeIndex(v) = *self; v }
/// Returns unique id (unique with respect to the graph holding associated node).
pub fn node_id(&self) -> uint { self.get() }
}
impl EdgeIndex {
fn get(&self) -> uint { let EdgeIndex(v) = *self; v }
/// Returns unique id (unique with respect to the graph holding associated edge).
pub fn edge_id(&self) -> uint { self.get() }
}
impl<N,E> Graph<N,E> {
pub fn new() -> Graph<N,E> {
Graph {
nodes: Vec::new(),
edges: Vec::new(),
}
}
pub fn with_capacity(num_nodes: uint,
num_edges: uint) -> Graph<N,E> {
Graph {
nodes: Vec::with_capacity(num_nodes),
edges: Vec::with_capacity(num_edges),
}
}
///////////////////////////////////////////////////////////////////////////
// Simple accessors
#[inline]
pub fn all_nodes<'a>(&'a self) -> &'a [Node<N>] {
let nodes: &'a [Node<N>] = self.nodes.as_slice();
nodes
}
#[inline]
pub fn all_edges<'a>(&'a self) -> &'a [Edge<E>] {
let edges: &'a [Edge<E>] = self.edges.as_slice();
edges
}
///////////////////////////////////////////////////////////////////////////
// Node construction
pub fn next_node_index(&self) -> NodeIndex {
NodeIndex(self.nodes.len())
}
pub fn add_node(&mut self, data: N) -> NodeIndex {
let idx = self.next_node_index();
self.nodes.push(Node {
first_edge: [InvalidEdgeIndex, InvalidEdgeIndex],
data: data
});
idx
}
pub fn mut_node_data<'a>(&'a mut self, idx: NodeIndex) -> &'a mut N {
&mut self.nodes[idx.get()].data
}
pub fn node_data<'a>(&'a self, idx: NodeIndex) -> &'a N {
&self.nodes[idx.get()].data
}
pub fn node<'a>(&'a self, idx: NodeIndex) -> &'a Node<N> {
&self.nodes[idx.get()]
}
///////////////////////////////////////////////////////////////////////////
// Edge construction and queries
pub fn next_edge_index(&self) -> EdgeIndex {
EdgeIndex(self.edges.len())
}
pub fn add_edge(&mut self,
source: NodeIndex,
target: NodeIndex,
data: E) -> EdgeIndex {
let idx = self.next_edge_index();
// read current first of the list of edges from each node
let source_first = self.nodes[source.get()]
.first_edge[Outgoing.repr];
let target_first = self.nodes[target.get()]
.first_edge[Incoming.repr];
// create the new edge, with the previous firsts from each node
// as the next pointers
self.edges.push(Edge {
next_edge: [source_first, target_first],
source: source,
target: target,
data: data
});
// adjust the firsts for each node target be the next object.
self.nodes[source.get()].first_edge[Outgoing.repr] = idx;
self.nodes[target.get()].first_edge[Incoming.repr] = idx;
return idx;
}
pub fn mut_edge_data<'a>(&'a mut self, idx: EdgeIndex) -> &'a mut E {
&mut self.edges[idx.get()].data
}
pub fn edge_data<'a>(&'a self, idx: EdgeIndex) -> &'a E {
&self.edges[idx.get()].data
}
pub fn edge<'a>(&'a self, idx: EdgeIndex) -> &'a Edge<E> {
&self.edges[idx.get()]
}
pub fn first_adjacent(&self, node: NodeIndex, dir: Direction) -> EdgeIndex {
//! Accesses the index of the first edge adjacent to `node`.
//! This is useful if you wish to modify the graph while walking
//! the linked list of edges.
self.nodes[node.get()].first_edge[dir.repr]
}
pub fn next_adjacent(&self, edge: EdgeIndex, dir: Direction) -> EdgeIndex {
//! Accesses the next edge in a given direction.
//! This is useful if you wish to modify the graph while walking
//! the linked list of edges.
self.edges[edge.get()].next_edge[dir.repr]
}
///////////////////////////////////////////////////////////////////////////
// Iterating over nodes, edges
pub fn each_node<'a, F>(&'a self, mut f: F) -> bool where
F: FnMut(NodeIndex, &'a Node<N>) -> bool,
{
//! Iterates over all edges defined in the graph.
self.nodes.iter().enumerate().all(|(i, node)| f(NodeIndex(i), node))
}
pub fn each_edge<'a, F>(&'a self, mut f: F) -> bool where
F: FnMut(EdgeIndex, &'a Edge<E>) -> bool,
{
//! Iterates over all edges defined in the graph
self.edges.iter().enumerate().all(|(i, edge)| f(EdgeIndex(i), edge))
}
pub fn each_outgoing_edge<'a, F>(&'a self, source: NodeIndex, f: F) -> bool where
F: FnMut(EdgeIndex, &'a Edge<E>) -> bool,
{
//! Iterates over all outgoing edges from the node `from`
self.each_adjacent_edge(source, Outgoing, f)
}
pub fn each_incoming_edge<'a, F>(&'a self, target: NodeIndex, f: F) -> bool where
F: FnMut(EdgeIndex, &'a Edge<E>) -> bool,
{
//! Iterates over all incoming edges to the node `target`
self.each_adjacent_edge(target, Incoming, f)
}
pub fn each_adjacent_edge<'a, F>(&'a self,
node: NodeIndex,
dir: Direction,
mut f: F)
-> bool where
F: FnMut(EdgeIndex, &'a Edge<E>) -> bool,
{
//! Iterates over all edges adjacent to the node `node`
//! in the direction `dir` (either `Outgoing` or `Incoming)
let mut edge_idx = self.first_adjacent(node, dir);
while edge_idx != InvalidEdgeIndex {
let edge = &self.edges[edge_idx.get()];
if !f(edge_idx, edge) {
return false;
}
edge_idx = edge.next_edge[dir.repr];
}
return true;
}
///////////////////////////////////////////////////////////////////////////
// Fixed-point iteration
//
// A common use for graphs in our compiler is to perform
// fixed-point iteration. In this case, each edge represents a
// constraint, and the nodes themselves are associated with
// variables or other bitsets. This method facilitates such a
// computation.
pub fn iterate_until_fixed_point<'a, F>(&'a self, mut op: F) where
F: FnMut(uint, EdgeIndex, &'a Edge<E>) -> bool,
{
let mut iteration = 0;
let mut changed = true;
while changed {
changed = false;
iteration += 1;
for (i, edge) in self.edges.iter().enumerate() {
changed |= op(iteration, EdgeIndex(i), edge);
}
}
}
pub fn depth_traverse<'a>(&'a self, start: NodeIndex) -> DepthFirstTraversal<'a, N, E> {
DepthFirstTraversal {
graph: self,
stack: vec![start],
visited: BitvSet::new()
}
}
}
pub struct DepthFirstTraversal<'g, N:'g, E:'g> {
graph: &'g Graph<N, E>,
stack: Vec<NodeIndex>,
visited: BitvSet
}
impl<'g, N, E> Iterator<&'g N> for DepthFirstTraversal<'g, N, E> {
fn next(&mut self) -> Option<&'g N> {
while let Some(idx) = self.stack.pop() {
if self.visited.insert(idx.node_id()) {
continue;
}
self.graph.each_outgoing_edge(idx, |_, e| -> bool {
if !self.visited.contains(&e.target().node_id()) {
self.stack.push(e.target());
}
true
});
return Some(self.graph.node_data(idx));
}
return None;
}
}
pub fn each_edge_index<F>(max_edge_index: EdgeIndex, mut f: F) where
F: FnMut(EdgeIndex) -> bool,
{
let mut i = 0;
let n = max_edge_index.get();
while i < n {
if !f(EdgeIndex(i)) {
return;
}
i += 1;
}
}
impl<E> Edge<E> {
pub fn source(&self) -> NodeIndex {
self.source
}
pub fn target(&self) -> NodeIndex {
self.target
}
}
#[cfg(test)]
mod test {
use middle::graph::*;
use std::fmt::Show;
type TestNode = Node<&'static str>;
type TestEdge = Edge<&'static str>;
type TestGraph = Graph<&'static str, &'static str>;
fn create_graph() -> TestGraph {
let mut graph = Graph::new();
// Create a simple graph
//
// A -+> B --> C
// | | ^
// | v |
// F D --> E
let a = graph.add_node("A");
let b = graph.add_node("B");
let c = graph.add_node("C");
let d = graph.add_node("D");
let e = graph.add_node("E");
let f = graph.add_node("F");
graph.add_edge(a, b, "AB");
graph.add_edge(b, c, "BC");
graph.add_edge(b, d, "BD");
graph.add_edge(d, e, "DE");
graph.add_edge(e, c, "EC");
graph.add_edge(f, b, "FB");
return graph;
}
#[test]
fn each_node() {
let graph = create_graph();
let expected = ["A", "B", "C", "D", "E", "F"];
graph.each_node(|idx, node| {
assert_eq!(&expected[idx.get()], graph.node_data(idx));
assert_eq!(expected[idx.get()], node.data);
true
});
}
#[test]
fn each_edge() {
let graph = create_graph();
let expected = ["AB", "BC", "BD", "DE", "EC", "FB"];
graph.each_edge(|idx, edge| {
assert_eq!(&expected[idx.get()], graph.edge_data(idx));
assert_eq!(expected[idx.get()], edge.data);
true
});
}
fn test_adjacent_edges<N:PartialEq+Show,E:PartialEq+Show>(graph: &Graph<N,E>,
start_index: NodeIndex,
start_data: N,
expected_incoming: &[(E,N)],
expected_outgoing: &[(E,N)]) {
assert!(graph.node_data(start_index) == &start_data);
let mut counter = 0;
graph.each_incoming_edge(start_index, |edge_index, edge| {
assert!(graph.edge_data(edge_index) == &edge.data);
assert!(counter < expected_incoming.len());
debug!("counter={} expected={} edge_index={} edge={}",
counter, expected_incoming[counter], edge_index, edge);
match expected_incoming[counter] {
(ref e, ref n) => {
assert!(e == &edge.data);
assert!(n == graph.node_data(edge.source));
assert!(start_index == edge.target);
}
}
counter += 1;
true
});
assert_eq!(counter, expected_incoming.len());
let mut counter = 0;
graph.each_outgoing_edge(start_index, |edge_index, edge| {
assert!(graph.edge_data(edge_index) == &edge.data);
assert!(counter < expected_outgoing.len());
debug!("counter={} expected={} edge_index={} edge={}",
counter, expected_outgoing[counter], edge_index, edge);
match expected_outgoing[counter] {
(ref e, ref n) => {
assert!(e == &edge.data);
assert!(start_index == edge.source);
assert!(n == graph.node_data(edge.target));
}
}
counter += 1;
true
});
assert_eq!(counter, expected_outgoing.len());
}
#[test]
fn each_adjacent_from_a() {
let graph = create_graph();
test_adjacent_edges(&graph, NodeIndex(0), "A",
&[],
&[("AB", "B")]);
}
#[test]
fn each_adjacent_from_b() {
let graph = create_graph();
test_adjacent_edges(&graph, NodeIndex(1), "B",
&[("FB", "F"), ("AB", "A"),],
&[("BD", "D"), ("BC", "C"),]);
}
#[test]
fn each_adjacent_from_c() {
let graph = create_graph();
test_adjacent_edges(&graph, NodeIndex(2), "C",
&[("EC", "E"), ("BC", "B")],
&[]);
}
#[test]
fn each_adjacent_from_d() {
let graph = create_graph();
test_adjacent_edges(&graph, NodeIndex(3), "D",
&[("BD", "B")],
&[("DE", "E")]);
}
}